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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 1434 (Transfer Case - NVG 126-NP4) >> Diagnostic Information and Procedures >> DTC C0305: Front Speed Sensor Malfunction >> Test Description

Test Description

WARNING: This page is about a different car, the 2004 Oldsmobile Bravada and 2004 Buick Rainier. However, it is still accessible from the selected car via links, so may be relevant.

The numbers below refer to the step numbers on the diagnostic table.

  1. 2:  This step tests to see if the malfunction is intermittent.
  2. 3:  This step tests the internal resistance of the propshaft speed sensor.
  3. 4:  This step tests to see if the propshaft speed sensor can generate a sufficient amount of AC voltage.
  4. 5:  This step tests the front propshaft speed sensor low signal circuit for a short to ground, a high resistance or an open.
  5. 6:  This step tests the front propshaft speed sensor high signal circuit for a short to ground, a high resistance or an open.
  6. 7:  This step tests the front propshaft speed sensor low signal circuit for a short to voltage.
  7. 8:  This step tests the front propshaft speed sensor high signal circuit for a short to voltage.
  8. 9:  This step tests the front propshaft speed sensor low signal circuit for a short to the front propshaft speed sensor high signal circuit.
DTC C0305

Step Action Value(s) Yes No
Schematic Reference: Transfer Case Control Schematics 
Connector End View Reference: Transfer Case Control Connector End Views 
1 Did you perform the Diagnostic System Check - Transfer Case? - Go to Step 2  Go to Diagnostic System Check - Transfer Case 
2 
  1. Drive the vehicle for a short test drive.
  2. With the scan tool, observe the value of the Front Propshaft Speed Data Parameter in the Transfer Case Data List while driving.
Does the RPM value vary while driving?		 - Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems Go to Step 3 
3 
  1. Turn the ignition OFF.
  2. Disconnect the transfer case front propshaft speed sensor.
  3. Measure the resistance of the transfer case front propshaft speed sensor.
Is the resistance reading within the specified values?		 1,300-2,700 Ω Go to Step 4  Go to Step 10 
4 
  1. Connect a DMM to the transfer case front propshaft speed sensor.
  2. Block the rear wheels.
  3. Place the transmission in NEUTRAL.
  4. Raise and support the front axle so that the wheels turn freely.
  5. Hold one front wheel while rotating the other front wheel.
  6. Observe the AC voltage reading on the DMM
Is the voltage reading greater than the specified value?		 0.5 V AC Go to Step 5  Go to Step 10 
5 
  1. Disconnect the transfer case shift control module.
  2. Test the front propshaft speed sensor low signal circuit for a short to ground, a high resistance or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Was the condition found and corrected?		 - Go to Step 12  Go to Step 6 
6  Test the front propshaft speed sensor high signal circuit for a short to ground, a high resistance or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Was the condition found and corrected?		 - Go to Step 12  Go to Step 7 
7  Test the front propshaft speed sensor low signal circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Was the condition found and corrected?		 - Go to Step 12  Go to Step 8 
8  Test the front propshaft speed sensor high signal circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Was the condition found and corrected?		 - Go to Step 12  Go to Step 9 
9  Test the front propshaft speed sensor low signal circuit for a short to the front propshaft speed sensor high signal circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Was the condition found and corrected?		 - Go to Step 12  Go to Step 11 
10 Replace the transfer case front propshaft speed sensor. Refer to Transfer Case Speed Sensor Replacement - Front  .
Did you complete the repair?		 - Go to Step 12  -
11
IMPORTANT: After transfer case shift control module replacement and reprogramming, ensure all doors are closed and the key is out of the ignition, then open and close the doors again and wait 2 minutes to avoid incomplete programming or setting false communication DTCs.
Replace the transfer case shift control module. Refer to Transfer Case Shift Control Module Replacement  and Transfer Case Control Module Reprogramming  .Did you complete the repair?		 - Go to Step 12  -
12
  1. Use the scan tool in order to clear the DTCs.
  2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.
Does the DTC set?		 - Go to Step 2  System OK
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